The present invention relates to organosoluble salts of manganese, to a process of preparting same, also to organic compounds, liquid fuels, paints and varnishes which contain said organosoluble salts of manganese.
Organosoluble manganese salts are used as oxidation catalysts in chemical operations and especially as combustion additives for liquid fuels of heat generating devices such as fuel oil burners, Diesel motors or propulsion engines, etc., and as drying additives in the paint and varnish industry.
According to prior art, the organosoluble manganese compounds are prepared by reacting a chelating agent in organic medium, such as aminated, borated, B-diketonic, cyclopentadienic derivatives, with a water-soluble manganese salt.
Another known process consists of reacting an alkaline salt of an organosoluble acid with a water-soluble manganese salt.
These reactions are substantially stoichiometric, i.e. the composition of the obtained compounds is such wherein one divalent manganese atom is essentially bound to two organic chains.
The so obtained organosoluble manganese compounds are rather expensive, especially the ones obtained from the B-diketonic and cyclopentadienic derivatives.
Moreover, a relatively large number of organic molecules in relation to the number of manganese atoms is needed for the processes according to prior art as indicated above, in order to obtain an organosoluble manganese compound that can be used as oxidation catalyst in the various chemical operations.
The aim of the present invention is to remedy these drawbacks by providing a solution resulting in low cost especially effective organosoluble manganese salts, having relatively low number of organic molecules compared to the number of manganese atoms.
Preferably, this solution also produces organosoluble manganese salts which are really soluble in organic solvents and oils, solubility attested by the absence of the Tyndall effect in the organic solutions of the foregoing salts.
According to the present invention this solution consists of organosoluble manganese salts which consist of complex organometallic salts of organic and organometalloidic acids, where the ratio R of the number of acid equivalents to the number of manganese atoms is lower than 2. In the present context the term of "number of acid equivalents" denotes the number of organic acid molecules when the acid employed is monofunctional, while this "number of acid equivalents" should be doubled or tripled in the case of the di and tri-acids, and more generally it should be multipled by the number of acid functions in the case of polyacids.
Preferably, the ratio R should be between 0.2 and 2.
According to a characteristic feature of the present invention, the organic or organometalloidic acids having at least one acid function, i.e. mono, di or poly-acid, is selected from among the organic or organometalloidic acids having from 8 to 30 carbon atoms and preferably from 8 to 25 carbon atoms.
It is advantageous for this organic or organometalloidic acids to have at least one carboxylic or sulphonic or sulphuric or phosphoric acid function and to perferably pertain to the following series:
aliphatic, saturated or unsaturated, straight or branched,
cyclic, may be alkyl-substituted, for example the naphthenic acids,
aromatic, if necessary substituted by an alkyl radical, especially the carboxylic alkyl-aryl acids, the sulphonic alkyl-aryl acids and the phosphoric alkyl-aryl acids,
terpenic, for example the resin acids.
Another aim of the present invention is to provide organic compounds, liquid fuels, paints or varnishes, which contain at least one organosoluble manganese salt according to the present invention.
The concentration of manganese in the organic compounds is relatively high and may reach 400 g of manganese per liter of said organic compounds. Nevertheless, these compounds retain a high degree of fluidity, since their viscosity ranges between 7 and 450 centistokes.
Moreover, said organic compounds indicate a very high degree of stability, since concentrated organic solutions of said organosoluble manganese salts never produce any precipitation of manganese oxide that would be equal to or greater than 0.5% of manganese in solution, even after one year of storage.
Another aim of the present invention is to provide a process of producing such organosoluble manganese salts, according to the present invention, by a method according to which a complex manganous ammine and an organic or organometalloidic acid of the foregoing kind are reacted in aqueous organic medium, by using a ratio R, i.e. the number of acid equivalents in relation to the number of manganese atoms is less than 2, and preferably between 0.2 and 2.
In the present context the term "complex manganous ammine" denotes a divalent manganese complex that comprises ammonia or ammine molecules.
The manganous ammine complex is conveniently prepared, in situ, by reacting in aqueous/organic medium which contains the foregoing organic acid, of an excess amounts of nitrogenated component such as for example ammonia, diethylamine or methylamine, with a water-soluble manganese salt. The water-soluble manganese salt should preferably be a manganous salt such as, for example, manganous sulphate, chloride, acetate, carbonate or nitrate.
The reaction is carried out at moderately elevated temperature, for example between 40.degree. and 60.degree. C., under agitation. At the end of the reaction, to promote separation of residual water originating mainly from the ammonia, and eventually of the water of crystallisation of the water-soluble manganese salt, from the organic phase, the temperature of the reaction medium is increased by 20.degree. to 50.degree. C. in comparison with the initial temperature of the reaction, so that said temperature at the end of the raction should preferably be between 80.degree. and 90.degree. C.
Furthermore, in order to obtain concentrated solutions of manganese, it is advantageous to add the water-soluble manganese salt and the nitrogenated compound in several successive steps into the organic phase. Also, the concentration of manganese in the organic solutions may be controlled by adjusting the proportion of solvent in the organic phase.
The organic phase is separated from water and solid particles by decantation and centrifuging.
The solutions obtained in this manner after separation may be added as they are, following adjustment of concentration, to liquid fuels, paints and varnishes as mentioned earlier, to serve, as required, as combustion additive or drying compound.